I think we can only make theories about Sylveon. The colors are quite misleading as you can see. I do think that Nintendo would make more impression and innovation in the world of Pokémon, I think we can expect a new type.
From Nintendo put an Eeveelution in the forefront of their new type, I'd be surprised. Can be seen in the page Sylveon its type is [???]. Maybe they do not want to mention it to annoy us. Or that it is a new type.
We will see!